


Left Unfinished

by dandelionknight



Series: Bubbline week 2019 [4]
Category: Adventure Time
Genre: Adventure, Bad Science, F/F
Language: English
Status: In-Progress
Published: 2019-03-23
Updated: 2019-03-22
Packaged: 2019-11-27 15:51:30
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,972
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18196220
Author URL: https://archiveofourown.org/users/dandelionknight/pseuds/dandelionknight
Summary: There's something strange hidden in pre-Mushroom War ruins. Princess Bubblegum, Finn, Jake and Marceline try to find out exactly what.





	Left Unfinished

The princess traipsed through stagnant pools and over the loose stones that littered the floor, eyes glued down and face lit up with a faintly greenish glow; she paid little mind to anything else. There wasn’t much to look at anyways, just grey walls a little too regular to be natural and the moisture that wept and trickled down their stony faces. 

Marceline floated beside her in the damp corridor of the cavern, lounging in the air; if she was going to be along for whatever ride Bonnibel and the boys were on she might as well do it in comfort. Although this adventure seemed less like ‘adventure’ and more like a subpar hike. Boredom tugged at her patience like an insistent child. 

“So, why am I here again?” 

It was silent save the walls echoing three sets of footsteps and Finn and Jake’s distant chatter somewhere farther in until Bonnibel spoke.

“Like I told you before; something in here is crazy powerful. Finn and Jake found it a few days ago and ever since then it’s been getting more volatile. Even what I have back at the cabin is going bananas– it’s giving off energy readings like you wouldn’t believe!”

Marceline scoffed, “I’m not sure if I believe that.” 

“Here, look!” 

Bonnibel tilted the device she held in her hands so that Marceline could see the screen and its wildly fluctuating lines and rollercoaster graphs the vampire assumed stood for some kind of important measurements. She raised an eyebrow.

“Looks very science-y.”

“Thanks – see this one?” the princess pointed to something rather like a speedometer only it was a full circle and the units were labelled wrong. The dial spun counter-clockwise a few times before making a rotation and a half back again. 

She kept her eyes on the screen as she walked and talked. It was a wonder she hadn’t tripped by now. 

“The existence of chronological residue alone would be reason to investigate but with the kind and amount of energy it’s giving off it’d be too dangerous to just leave alone, at least not until we’ve run some proper tests.”

“I can get that. But seriously Bonnie, why am I here? You’ve got Finn and Jake and your big ol’ brain. Not that I wouldn’t want to go chasing some chrononphenomenon or whatever but I’m not sure if this is exactly my specialty, you know?” 

“Well, if it turns out that it can’t be explained by science,” the princess made a small, derisive noise in the back of her throat, “you know a lot more about magic than I do and you’re much easier to deal with than any wizards.”

“But –“

“And I like hanging out with you. Having adventures like we used to. So… I thought I’d invite you along.”

The princess tore her gaze away from her machine for the first time in a long while and smiled up at her best friend, her face perhaps a little pinker than usual.

“Oh.”

She had many, many more things to say to Bonnibel than ‘oh’. Marceline flipped herself vertical and drifted down closer to the other woman’s level. The vampire opened her mouth a couple of times, but none of the words buzzing like bees in her brain came out. They flew and walked in silence until Finn’s distinctive scream broke it and a deep thump reverberated through the tunnel. Eyes met and they exchanged a look, one less of concern and more of a cautious sort of curiosity.

“They’re probably fine,” Marceline said.

Two sets of footsteps, rapid slaps against the stone that echoed through the corridor. The two brothers came barreling towards them, the flashlights strapped to their heads (and hat) casting strange, bouncing shadows in the gloom.

“Gals, gals, gals, gals!” the teenager gasped as he bent forward, hands on his knees, “I think we found the thing. And a shortcut.”

“Seriously, you gotta see it, it’s beautiful,” Jake’s large eyes shone with unshed tears. With a little shapeshifting they became even bigger, practically glittering. “Bea-u-ti-ful.”

Both women squinted before the adventurers realized they were blinding them. The boys reached up to click off their lights. 

“Oh, woops!” 

“Sorry, our bad.”

Bonnibel finally pocketed the device, at least for now, and blinked away the spots that flickered across her vision. 

“Alright then boys, lead on!”

The corridor curved left, then right before they all stared down into the fresh new pit the brothers had stumbled into. A pebble was kicked into it and a fair number of seconds passed before anyone heard the clattering of its landing. The princess rummaged through her pack and produced a rather more heavy duty flashlight of her own, flicked it on and shone it into the depths. The jagged edges of other floors that had been broken through stood out starkly against the darkness. A great pile of stony rubble lay in a heap at the very bottom.

“That’s a long fall, how did you two make it back so fast,” Bonnibel asked.

“I have my ways,” Jake answered, wiggling his fingers at the group, “Mysterious ways.”

“He stretched us back up.”

“Finn! You’re ruining the mystery,” Jake half groused, half joked.

He looped his arms and legs around the teen like a harness: a living parachute. 

“Fivefourthreetwoone gooooo!” And with that, Finn launched himself into the pit, whooping all the way down, mixing with Jake’s laughter.

The princess returned her things to her pack and slipped the straps over her shoulders. She shrugged and made eye contact with Marceline who nodded in unspoken agreement. She too leapt over the edge and Marceline flew in after her. 

The candy princess kept one hand on her crown while she plummeted toward the stone. It was exhilarating rather than terrifying and she let out her own shout of joy. After all, there was no real danger; a strong arm wrapped around her waist prevented the princess from meeting a grisly end. 

“Thanks for the lift Marcy.”

“No prob,” the vampire smiled and set the other woman lightly on her feet. 

“Come on you two it’s this way,” Jake called.

Bonnibel squared her shoulders and retrieved her glasses from one of the many pockets of her jacket to put on what Marceline privately thought of as her ‘science face’.

“Let’s go.”

\-----

The old iron door was already swung open and inward. Inside the chamber was surprisingly well lit; intermittent strips of warm light flickered to life like stars to reveal what seemed to be a shrine to a half-finished endeavour. Ancient dust tickled their noses as they entered. One corner was devoted to various materials and tools arranged to someone’s esoteric preferences. Along the right wall stood an array of old world technology: holographic projectors, empty computer stations and various other devices. The brothers had already begun fiddling with a projection of near space, its planets and cycles, while beautiful, were a thousand years out of date. Marceline gravitated to some old computer in the far corner searching for any hint of life in the dusty old tech. However, the majority of the room was taken up by the machine. 

Thick red and blue cables snaked into it from over and under the four corners of the room. Bonnibel stepped over them as she approached. She could see the heart of it through gaps in its incomplete metal skin; it was of an elegant design, powerful yet relatively compact. A keen eye noticed what looked like stabilizers leaning against the wall and the beginning of fuel lines and a pump heaped nearby. At a glance, it seemed like some kind of spacecraft. It was a shame that it would never fly.

She gave a cursory glance at the schematics littering the floor; none of it was new to her save the name. 

“The Remembrance,” she read aloud. 

“So whatcha think PB? Is that thing the thing we’re looking for?” Finn asked. 

She checked her Thingamatron but there was no response.

“Nope. Just an interesting piece of history.” She rested a hand on it the cool metal surface, her eyes distant. “I suppose is pretty in a melancholy sort of way, Jake.”

“What that? I meant this sweet game I found!” 

He had discovered a controller among the wide variety of junk and was using it to shoot down holographic spaceships. If the numbers hovering near the lower range of the projection were any indication he was doing quite well. 

“Does BMO mind you playing other games?”

“Nah, BMO’s cool,” Jake answered between waves of attackers. 

Finn had wandered off, checking one of the doors leading out. She walked over to Marceline, peering over the older woman’s shoulder. 

“Find anything interesting?” 

“Just a flash drive and somebody’s weird scrapbook,” she handed her a black binder, the plastic covering peeling back from its cardboard frame at the corners.

Bonnibel flipped through the pages of taped-in photos and tiny crammed handwriting. 

“They look human.”

“Probably were. This is all pre-war stuff. I’m still trying to get this thing to turn on properly.” 

“Maybe I can help with that.”

Bonnibel caught a glimpse of a devilish grin.

“I bet you –“

The princess cut her off before she could finish. “Is it the hardware or a software problem?” 

She sighed, “Software, I think. I’ll figure it out.”

Bonnibel set the book aside and brushed past her.

“I’m sure you will; you’re really good with computers.”

“Thanks Peebs.”

Marceline returned her attention to the keyboard and screen in front of her. 

Picking through the tools and scrap pieces one by one she scanned them, but none so far were the power source. It was tedious work for about forty minutes, punctuated only by the click of Jake’s controller and the clack of keyboard keys. Her mind wandered.

“What you think all this was for?” 

Jake shrugged, unseen, as he continued to play. 

“To shoot something into space? Why else would you build a rocket?” Marceline quipped. 

The princess rolled her eyes at the remark. “Well, yes, but was it for exploration or a more specific purpose? Where’s the payload?” She tapped her fingers idly on a wooden crate. “Does that computer have any hints?”

“Just more designs – I don’t really know what of and it never mentions what they’re for though. It sure doesn’t look like that thing,” she gestured to the hulk, “Besides; they were using code words for the important bits –just stuff like ‘piggyback’ and 'echo'.” 

“You know who made it?”

“Haven’t gotten that far yet. Whoever did was mad security conscious.”

The three of them returned to their own tasks, although Jake had never actually stopped playing his game. 

“PB I don’t anything’s here,” Jake said after another ten minutes and his last life.

“Me neither,” Marceline echoed. 

Bonnibel sighed, “Alright, let’s get out of here. It’s strange; since we came in here I haven’t gotten so much as a twitch on the Thingamatron.” She smacked the device and gave it a brief shake. “Oh wait never mind. It’s flipping out again.” 

“Hey guys? I think I found something weird in Dan’s room,” Finn shouted from somewhere deeper in the ruin. 

“Dan?” Marceline looked to Bonnibel. The princess shrugged. 

“How weird are we talking?” asked Jake. 

“Uhhhh… reasonably? Like reasonably weird,” came Finn’s distant reply. 

The three exchanged a collective look and walked out of the room and into a dim, narrow hallway toward his voice. 

Jake called out to his brother, “Finn?”

“In here!”

They filed into a room much longer than it was wide. Parallel sets of metal, utilitarian shelving lined the grey, concrete walls. Unlike the other room, its contents were mostly neatly labeled and stacked. A book stood tucked near the light switch, its well-worn spine posing the question ‘So, you want to live forever?’ The princess made a mental note to pick it up on the way out. There was a shelf devoted to yellow and black plastic containers and another to jugs and bottles of various chemicals, another of hard drives and computer chips and yet another to what appeared to be jarred bits of biological matter. 

Jake swirled one with a bleached out brain in bluish fluid. It bumped against the glass.

“Heh heh, gross,” he said before placing it back down.

The far end of the room was thick steel and the remainder of a yellow sign with bold black text hung just below a sliver of a window on a door, the surviving letters spelling out ‘Dan Do Enter’.

Finn struggled, turning a vibrant red as he laboriously pried the door open. 

“It kinda looks like your lab Peebles but way, way creepier,” the boy said. 

“I’d say it rates on the ‘reasonable’ scale, yeah,” Jake remarked, “It’s got good ambiance without sacrificing lighting. Sort of a mad science-chic kinda thing.”

“Well… we found Dan,” Marceline finished. 

Skeletal remains dressed in the majority of a lab coat sat strapped into a repurposed dentist’s chair, its bone fingers still gripping the armrests and head tilted back. The jaw hung open and its squarish, blue plastic glasses reflected the singular light above. 

Like the spaceship, a network of wires hooked up the body to devices around the closet of a room. Or would have if it still had any flesh. A monitor, long since disconnected, was mounted from the ceiling so that ‘Dan’ could see it and a control panel, along with a handful of wires and tools, rested on a metal wheeled table within arm’s reach. 

The boys set to work rummaging through a filing cabinet and Bonnibel sifted through the handwritten notes scattered on the L shaped counter running along two walls.

Marceline traced several, delicate wires that snaked through a clear case and connected to a little black cube, not even half the size of one of her guitar picks. It just sat there in its case when she tapped it. 

“Hey, what do you think this thing is?”

“Hmm?” The princess looked up from a stack of papers and came over to inspect the item. “I’m… not sure...” 

The brothers wandered over as well.

“There’s stuff in the cabinet but it’s all really boring,” Finn said.

Jake cocked his head sideways and sniffed the case. He went to lick it but Bonnibel pushed his head back. 

“This seems pretty boring too.”

She took the machine from her pocket and turned it on. Immediately it began dinging. “Maybe, but I guess it’s what we’re looking for.”

She dug through her backpack, removing a set of gloves, tongs and a mason jar labeled ‘Specimen _ of _’. 

“You really need all that?” Marceline asked.

“I don’t know,” she replied while pulling on the gloves. “But safety never hurt anyone.”

There was a hiss, like opening a can of soda, when she lifted the protective cover and an almost inaudible beep.

“You hear that?” Finn asked, brow furrowed.

The princess fiddled with her device again, and then unscrewed the lid of the jar in preparation. 

“Don’t worry; the gas is harmless in small quantities.”

She plucked the cube from its resting place. As she carried it, one hand under to keep it from falling, the cube flattened and then popped six arachnid legs from its chip of a body. It skittered up the tongs.

“Uh… could you bring that jar over here?” It crawled higher. “Quickly please.”

Finn rushed over.

“Some kind of robo-bug?”

She hummed ‘I dunno’ noise and flipped the tongs sideways to brush it off into the container with no success; it simply crawled up to remain on the top of the tongs. 

It sat completely still for a moment, as if calculating its next move. 

It leapt from its perch onto Finn’s shirt. With the startling speed of an uncovered spider it raced up the blue fabric and up under his hat.

A full body shudder ran through him and he screamed through gritted teeth.

“Get it off! Get it off! 

He ripped off his hat, shaking it violently with one hand while swatting at his long, unkempt hair with the other. It simply crawled onto the edge of his shoulder, a minuscule red light blinking once on its tiny body before it jumped again, somewhere out of sight. 

“Where is it?!” 

“I don’t know!”

“Oh good Glob it’s in my ear!” 

Jake flopped to the ground and kicked at it, well, like a dog. Another flash of red and it disappeared. 

Marceline hovered high up toward the ceiling, eyes scanning for any sign of the thing. 

“Let’s regroup!” Finn suggested.

Everyone agreed. 

All four bolted for the door, tripping over their feet and each other as they slammed it shut. Jake stretched out an arm all the way to the first room and grabbed a chair, jamming it under the handle.

“There we go. Safe.”

The friends breathed a sigh of relief.

“Anyone know a bee keeper? Or an etymologist? Finn asked.

“Entomologist,” Bonnibel reflexively corrected. 

“Ugh,” Jake groaned, “I can still feel it in my ear.” 

They made their way toward the first room to plan their next move. Marceline remained high above the group and was, frankly, content to stay there. She cast a glance behind them. Something flickered in the corner of her vision, near the long, thin window.

She shook her head and looked again. There was nothing.

\-----

They sat in a sort of circle in the main room, near the old computer. 

“So, what’s the plan?” Jake began. 

“Catch it and let Bonnie science it to her heart’s content. Then, maybe crush it,” Marceline offered.

“Good start,” Finn said, “but how?”

“Well I didn’t bring my supersonic butterfly net so we’re at a serious disadvantage here.” Bonnibel said, “I was thinking that although it has –”

“Did you hear that?” Jake interrupted.

_Beep._

“Jake don’t joke man, it was in my hat!”

“I’m serious!” 

_Beep. Beep beep._

The thing was scuttling around on the ground a hair to the left of Finn's shoe. 

Chaos erupted. Finn stabbed at the floor several times but only managed to ding his sword. Jake shifted his hand into a massive flyswatter, smacking at any possible targets; mostly larger pieces of lint and dust bunnies. Marceline threw a boot at it. All the while, Bonnibel yelled that they didn’t know what consequences destroying it might have and for everyone to just calm down.

Mid shout, the princess felt something tickle over her palm. She flipped her hand and saw the former cube, now robo-bug, sitting contentedly. It winked green once, chimed softly, and dug its sharp legs into her wrist.

She cried out and tried to shake the tenacious thing loose but it stuck fast. It was wriggling, burrowing into her flesh. That brilliant mind of hers had nothing to contribute; she slammed her hand against the desk in the corner, jolting the computer monitor and nearly sending it to the floor. 

With bated breath, she looked at where it had been. No sign of the robo-bug itself, not even its remains. 

“Did it get you?” Finn asked, looking concerned. 

“I… I think it bit me. It’s gone now.”

Marceline hovered, literally and metaphorically, just behind her. 

“Are you ok?” 

The princess gave her a reassuring smile.

“I’m alright Marcy, it’s gone.” 

She gently took her friend’s hand and examined her wrist; six little punctures and a messy horizontal slice. She sucked a breath through her teeth.  
“Nothing a lollipop and a band aid won’t fix,” the younger woman insisted. 

The smile stayed in place but became the brittle sort Marceline knew, from previous experience, meant that she was lying through her teeth. Marceline wasn’t sure who exactly she was reassuring. Candy biology was pretty strange but there was something more to it. Something nagged at the back of her brain.

“What about all those weird graphs? And the chronons?” 

“Nothing terrible or weird has happened so I must have been wrong.”

“You don’t hear that too often,” Marceline joked and then instantly wanted to bite off her own tongue. 

Eye down, Bonnibel agreed, “Yeah. Yeah, I guess so”

Finn and Jake took turns looking at the bite before she wrapped it with some gauze for a first aid kit she kept in her pack. She reassured them that no, she wasn’t poisoned and that no, most robots were neither poisonous nor venomous. 

They gathered up a few things they wanted to scavenge: a novelty mug Marceline liked the shade of as well as her, now scuffed, leather boot and the book Bonnibel had seen earlier. The boys, packrats that they were, snagged a few bits and pieces for the treehouse, although Jake left behind the game he had been playing. 

“Sorry we couldn’t bring some crazy scientific marvel back like you wanted,” the young adventurer said, his own way of clearing the air. 

“Its fine, Finn. It can’t fall into unscrupulous hands now so it all worked out,” the princess shrugged. “Speaking of which, what’s with the uh…” She leaned forward to read one of the many bottles in his arms, "Acetone?”

“Honestly I was just grabbing everything that said ‘flammable’.” 

Her eyebrows shot up, “Why?”

“Well, it’s almost FP’s birthday,” he scuffed the unfinished concrete with his shoe, “and I mean I still want to get her something, you know? It’s like, we’re cool and all now, and so I want to get her something neat, in that friend way, and I figure she likes fire and explosions so an armful of flammable liquids…” He trailed off, looking at the haul of chemicals,”….seemed like a good idea when I picked them all up a minute ago.”

“It’s a great idea,” Marceline reassured him. “Girls love explosions, right Bonnie?” 

“As fireworks or in a controlled lab setting, absolutely yes.” She looked at Finn, a serious expression on her face, “ _No one_ likes surprise explosions.” 

The boy nodded.

“And maybe don’t just toss those in your backpack.”

\-----

They made good time back to the treehouse with only one detour to Squeez-e Mart for a quick junk food run. Unfortunately, the rather jaded cashier wasn’t fazed by the appearance of a bat monster so they still had to pay full price. With a noodley wave from Jake and a regular one from Finn, the boys went home for the night, crunching on some limited edition Real Potato™ corn chips. 

And it was just the two of them.

“What’re you up to after this?” Bonnibel asked.

“Oh, I thought I’d watch that Heat Signature spin-off, Cold Sign, and work on some a few songs.”

“That’s right – you have a new tour coming up, don’t you?”

“Yeah,” Marceline said and explained her route through some of the neighbouring kingdoms and direction for her music.

The princess listened attentively and, when the conversation finally lapsed, the silence between them wasn’t the same as it was before their reconciliation in the candy mines and the devampification process; no hurt feelings hid in the quiet to ambush with accusations and heated words. There was no rush to fill the air. It was comfortable. 

Safely on the balcony, the vampire turned to her friend, the ghost of a smile playing on her lips.

“And what are you doing tonight?”

“Just some light science-ing and then to bed. I have a meeting with President Porpoise tomorrow morning.”

The older woman leaned against the rail, letting her legs dangle in the air.

“Sounds exciting,” she teased.

“Oh, it is,” the princess dryly remarked, “Negotiating nautical defense treaties is the kind of thing people write books about.”

“Yeah but only the boring ones.”

Dark eyes turned warm and the vampire added, “But good luck anyways.”

“You too.”

The pair lingered. Silence settled. Night fell. 

“Aren’t you gonna thank me for the ride?” 

Bonnibel rolled her eyes but smiled, “Thanks Marcy.”

**Author's Note:**

> Here's the fifth prompt: memories. This one got away from me a bit, but it will be continued when I have a little bit more time c:  
> Thanks as always for reading!


End file.
